The present invention relates to particulate filters in fluid systems and particularly relates to fluid systems of the type utilizing hydraulic fluid or engine oil and more particularly relates to the flow of fluid in an hydraulic operating circuit of an internal combustion engine valve deactivation system.
In certain motor vehicle engine applications, it is desired to provide a filling access port into the valve deactivation hydraulic circuit for adding fluid in service and for sealing the service port after filling. The filling access port must be located conveniently for gravity filling and yet be sealed after filling to withstand the operating pressures and flow during operation of the engine. In order to provide a convenient location and proper access to the deactivation hydraulic circuit and accommodate gravity fluid filling, it has been necessary to locate the filling access port in such a manner as to experience reverse flow to a branch passage during operation with respect to the gravity flow during filling. Where it is desired to provide filtering of the fluid during filling and during engine operation, this port arrangement has complicated the use of a cartridge type filter for protecting the fluid in the circuit from contamination during filling and during engine operation.
Accordingly, where a fill port is provided into the engine valve deactivation hydraulic fluid circuit and where the fill port is sealed after filling through fill port by a removable plug, it has been desired to provide a filter in the fill port to prevent introduction into the transmission of any contaminants or foreign material which may be present into the fluid added and to provide filtering of reverse direction fluid flow during engine operation.
The problem is further complicated where the fill port taps into a flow passage in the fluid circuit to form a three-way junction. Such an arrangement provides for fluid fill by gravity into the engine oil sump through vertical branch of the passage. When the removable plug is inserted and sealed after completion of filling, reverse flow is encountered to the other branch, thus backwashing any foreign material or contaminant trapped by the filter during fluid filling. Accordingly, it has been desired to provide a simplified and low cost removable filter cartridge which could provide for bi-directional flow in the fill port and also provide for flow to a branch without permitting foreign particles or material trapped during filling from being backwashed into the operating circuit.
The present invention provides a generally cylindrical filter cartridge assembly insertion into a fluid flow circuit such as for use in an engine valve deactivation hydraulic circuit. The cartridge is inserted in a fill port provided in the fluid circuit and is retained and sealed therein by removable plug after the addition of fluid to the system through the fill port. The cartridge provides for reverse axial flow therethrough during filling and reverse axial and radially outward flow to a branch circuit upon insertion of the removable plug after filling and prevents foreign material which may be trapped in the filter during filling from entering into the fluid circuit through the branch channel during engine operation. The filter is a one-piece removable cartridge which is insertable in the fill port and sealed therein.
The filter of the present invention has a generally cylindrical configuration and is preferably formed of screen material with one end open and a wall of screen material closing the opposite end of the cylindrical configuration. The screen material is overmolded with plastic or engineered resin material to form axially spaced annular support ribs with an annular seal provided thereabout for isolating the branch channel in the fluid circuit to permit reverse flow axially through the transverse screen and radially outward flow to the branch channel. In the presently preferred practice, the screen material is overmolded by injection molding with the screen material comprising a cylindrical piece and a flat disc shaped piece for the closed end in one embodiment and a tapered piece in another embodiment which pieces are inserted into a mold for overmolding for forming a one-piece filter cartridge. The present invention thus provides a novel removable filter cartridge for providing filtering during bi-directional axial flow and radial outflow with filtering and which is low in cost, relatively easy to manufacture and provides complete stiffening of the filtering material by overmolding with plastic stiffening ribs.